Atom location by channelling enhanced microanalysis (ALCHEMI) under a planar channelling condition was performed to locate the ternary additions Fe, Co and Cr of about 5 at% in the intermetallic compound Ni₃Al. It is concluded that the occupation site of Fe atoms depends on the chemical composition of the compound, i.e. the averaged Ni site occupancies of Fe in Ni₇₀Al₂₅Fe₅, Ni_72.5Al_22.5Fe₅ and Ni₇₅Al₂₀Fe₅ are 70%, 42% and 23%, respectively. The Ni site occupancy of Co in Ni₇₀Al₂₅CO₅ is 94%, but that of Cr in Ni₇₅Al₂₀Cr₅ is 6%, showing that Co and Cr have strong preferences in the Ni and Al sites, respectively. These results are compared with previous results obtained by APFIM and ALCHEMI under an axial channelling condition and the predictions from the thermodynamical consideration on the phase diagram. The accuracy of ALCHEMI under a planar channelling condition is also discussed for the L1₂-type ordered structure.